Most parents in the U.S. have spent the past few days imagining what it would be like to be the mother or father of one of the 20 schoolchildren murdered on Dec. 14 in Connecticut. Each detail that emerges from that stricken community brings many of us to tears. And of course we think, What if a madman came to our child’s school in a rage with a gun?

But there’s another group of parents who watched this horror story unfold with an opposite and perhaps more excruciating thought: What if the madman were my child?

Parents of mentally ill children and young adults can’t say they are afraid of their own children or admit that they know what it’s like to have bright children whose rages could, under circumstances they can’t predict, lead them to kill innocent people the way Adam Lanza is alleged to have done at Sandy Hook Elementary. And they can’t find comfort in the wake of a national tragedy by sharing their feelings around the watercooler like the rest of us.

But this week, one of these mothers stepped forward with an eloquent, wrenching cry for help that has echoed across the Web. In a blog post republished on the Blue Review titled “I Am Adam Lanza’s Mother,” Liza Long writes, “I live with a son who is mentally ill. I love my son. But he terrifies me …”

She goes on: “I am sharing this story because I am Adam Lanza’s mother. I am Dylan Klebold’s and Eric Harris’s mother. I am James Holmes’s mother. I am Jared Loughner’s mother. I am Seung-Hui Cho’s mother. And these boys — and their mothers — need help. In the wake of another horrific national tragedy, it’s easy to talk about guns. But it’s time to talk about mental illness.”

Long describes the love she has for her 13-year-old son, a brilliant boy who loves Harry Potter and has a “snuggle animal collection.” But according to her, this same child has also threatened her with a knife so many times that she keeps a Tupperware container for the days she has to collect all the sharp objects in the house. Nothing really helps, she says, not the powerful meds, the intermittent hospitalizations or what she calls a “Russian novel of behavioral plans.” She says she has trained her other children to lock themselves away for their own safety when their brother falls into one of his unpredictable rages.

She lays out the agonizing choices she says she’s been given, including having her child charged with a crime so that he is put in prison, a place that would surely exacerbate his symptoms and not necessarily keep him or the community safe. After all, you can’t keep someone indefinitely locked up for a crime they haven’t committed and will likely never commit.

It’s a world of family turmoil that most of us can’t begin to comprehend and which may or may not be similar to the struggles of Adam Lanza’s mother. In any case, Long’s essay resonated, and the response has been enormous. The piece has been forwarded endlessly on Facebook and reblogged by national media sites. And more than 1,500 people have commented on Long’s original blog post.

Most commenters wrote to express their sympathy, but there were also many who wanted to tell Long she is not alone. These are people we don’t normally hear from unless a tragedy occurs. They are the mothers, the fathers and the siblings of boys like Michael. These are the parents who report having to hide their knives or sleep with their bedroom doors locked. And in some cases, the commenters are young men who say they are plagued by the same demons as Long’s son.

Their testimonies form a trail of heartbreak that stretches for dozens of pages.

“Your story is my story and it is a very scary and often lonely path,” writes one parent. “As my son gets older and stronger the fear of what may be looms closer and closer and I just want to have the smart, sensitive sweet boy with me all the time, not the boy that when he says he wants to kill me, I believe him. The boy who wants to be tucked in at night with his stuffed animals and snuggles our dog, not the boy who can lift me off the ground in a rage and slam me into a wall. I pray daily for some kind of help.”

“Rachael” writes to say that her brother is a boy like Michael, offering evidence of the pain mental illness can cause a family: “I can’t believe it. You just described my brother. They say he’s aspergers, but I don’t know if that accounts for all of it. He’s normally really sweet, sensitive, and very very smart, but when he snaps, he curses, hurts people, throws things, threatens suicide, and pulls knives. I have scars from where he’s scratched or strangled me.”

Some commenters sent suggestions for treatments that have worked for them, from diets to 24/7 hospitalization. Some even suggested that Long subject her son to an exorcism, which speaks to the long-standing and devastating connection that is made between mental illness and evil.

And perhaps the most striking comments came from boys like Michael: “I was your son,” writes one. “I feel for you and him both. You sound exactly like my mother, to a T. It is really hard to see these scenarios play out for another family. I feel for you and him both. I refused pharmaceutical medication and bucked every diagnosis thrown at me.”

This young man goes on to say that spending time in nature, watching comedy and listening to the radio call-in program Loveline helped him. But for so many, the problem is beyond that. And for parents, the years after their troubled children leave home are just as fraught as the time before. “Robert” writes, “We have a son with mental illness. Now that he is an ‘adult’ in the eyes of the law, he’s decided he does not want to pursue any sort of treatment. Our hands are tied.”

With mass murders increasing in frequency, getting troubled people treatment is a national issue. Nevada and New York are among a few states that have some legal measures parents and relatives can take (with the recommendation of psychiatrists) so that people over the age of 18 get outpatient psychiatric care when warranted. But often, mothers and fathers are left with the all the worry and very little control. (Those laws, like Kendra’s Law and Laura’s Law, are named for people who have been killed by the mentally ill.)

And it’s because of the terrible specter not just of more massacres but also of the numerous other incidents of violence that don’t make the news that Long’s post has become a rallying cry for those fighting to get increased access and funding for mental-health services. “HOW CAN WE HELP?” asked one of the commenters. It’s a question the nation should certainly be asking as we debate how to prevent tragedies like the one that has devastated Newtown.